Opencart code

General information for the website: We sell personalised candles
Description of requirements/features: Hi - We are developing an updated OpenCart shopping cart in the backend of our existing site. I'm getting the following type of error (pasted below), when adding certain drop down options to some products. It appears to begin appearing when multiple options are selected and added.

I believe it could be due to some coding in the vqmod module.

We would like this glitch ironed out before progressing with the build too far.

Site: www.candles-online.co.uk/store
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Notice: Undefined index: points in /home/candl574/public_html/store/admin/model/catalog/product.php on line 127Notice: Undefined index: quantity in /home/candl574/public_html/store/admin/model/catalog/product.php on line 173Notice: Undefined index: subtract in /home/candl574/public_html/store/admin/model/catalog/product.php on line 173Notice: Undefined index: price in /home/candl574/public_html/store/admin/model/catalog/product.php on line 173Notice: Undefined index: price_prefix in /home/candl574/public_html/store/admin/model/catalog/product.php on line 173Notice: Undefined index: points in /home/candl574/public_html/store/admin/model/catalog/product.php on line 173Notice: Undefined index: points_prefix in /home/candl574/public_html/store/admin/model/catalog/product.php on line 173Notice: Undefined index: weight in /home/candl574/public_html/store/admin/model/catalog/product.php on line 173Notice: Undefined index: weight_prefix in /home/candl574/public_html/store/admin/model/catalog/product.php on line 173Warning: Cannot modify header information - headers already sent by (output started at /home/candl574/public_html/store/admin/index.php:85) in /home/candl574/public_html/store/vqmod/vqcache/vq2-system_engine_controller.php on line 28Warning: Cannot modify header information - headers already sent by (output started at /home/candl574/public_html/store/admin/index.php:85) in /home/candl574/public_html/store/vqmod/vqcache/vq2-system_engine_controller.php on line 29

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Quotes for fixing please.
Payment methods: Paypal
Extra notes: